It's about one-thirty-five-thousandth the number of Users on Facebook.

In other words, the count of Users on Facebook is 36,900 times 39,000.

(March, 2015 figures) (monthly active users)
Facebook had 1.44 billion active users for the month ending March, 2015. In August, 2014, Facebook began a process of removing 87 million accounts that it had found to be fake.

It's about one-one-thousandth the number of people in The State of California.

In other words, 39,000 is 0.001017 times the count of people in The State of California, and the count of people in The State of California is 983.3 times that amount.

(2014 figures) (Department of Finance estimate)
California, the most populous state in the United States, is home to 38,340,000 people (larger than the population of the entire country of Canada, with 35,540,419 people). Over ten percent of the population — 3,904,657 people — reside in the city of Los Angeles.